how did the frog scheme to destroy the nightingale's spirit and destroy her?

The theme as well as the allegorical significance of the poem is that one should not forsake their individuality and originality by playing to the gallery. Our individual talents are what make us unique in the world and there will always be people like the frog who want to pull down creatures like the nightingale. The nightingale did not have the necessary circumspection required to navigate the world and she was quite gullible. This is a comment on those writers who become famous due to their original craftsmanship but then become misguided by the people around them, especially critics who presume to know more about writing than writers themselves. Thus, the frog's non-stop criticism and training made the nightingale lose her voice and her singing became mechanical and uninspired, ultimately leading to her downfall. ​The frog was extremely envious of the nightingale. He felt threatened by the nightingale's talents and decided to use his cunning to destroy the rising star. He pretended to be a famous critic and duped the gullible bird into accepting him as her mentor. The naive bird, flattered by the attention and advice of the frog, lacking in self-confidence and powers of discretion, felt privileged to be bestowed with attention from the frog. This made the frog's job easier because now he could manipulate her directly and which he did, using her talents to make money for himself. He made the bird lose its voice by criticizing her, training her to hone her talents in such a way that more money came in and pushing her over the edge by wounding her already low self-esteem. Although it was the frog who wanted the nightingale to sing according to what he thought the audience wanted to listen. It shows that the frog was a highly cunning, manipulative and shrewd creature who make a complete fool out of other creatures like the poor bird who wasn't as sharp as the frog.